For many years, both government and industry standards have been promulgated to reduce accidental poisoning or injury to children by making it relatively difficult for young children to open certain types of containers, for example, pharmacy vials containing drugs. Unfortunately, most of the developments which make containers difficult to open by children also make the containers difficult to open by adults. This is especially true of adults having limited manual dexterity, such as both younger and older adults suffering from arthritis and other diseases or those having injuries which lessen manual dexterity.
Various prior art devices have been developed which attempt to provide both a difficult to open container when the product is being used in the presence of children and an easy open container for persons having limited dexterity. One such device of this type is described in applicant's U.S. Pat. No. 4,353,483 which included a bipositional hinged tab which makes the cap easy to open when in one position and relatively difficult to open in another position.
Unfortunately, the prior art devices have had somewhat mixed success with children, since children can be quite creative in opening containers. This is especially true where a child is willing to use his or her teeth to attempt to open the lid of a container. A child is often able to make up for a lack of manual dexterity or the inability to understand how to open the lid through the strong pressure that can be exerted by the teeth and can often pry the lid open or bite off portions of the latch to allow the lid to open. Certain prior art devices have attempted to circumvent this problem by positioning guard members to keep children's teeth from engaging the lifting tab (for example, see U.S. Pat. No. to Stull No. 3,826,394). However, none of the prior ar devices has highly effectively and inexpensively combined a structure which can be configured for easy opening by adults and yet can be configured to inhibit opening by young children.
It is becoming increasingly evident to product safety specialists that closure members for certain types of containers, especially pharmaceutical vials, should be designed such that the lid once attached to the body is always maintained connected to the body of the container and preferably such that the lid can be closed using a single hand. That is, that a user can both swing the lid into a closed position while holding the vial with the same hand that is being utilized to swing the lid and that the lid will then automatically lock in a secured configuration when the lid is closed. This concept is frequently referred to as "one hand and one motion to close".
It is desirable that the container include a hinge for connecting the lid to the body of the container that is difficult for a child to manipulate and, thereby, open the container by disassembly of the hinge. There is also a need in the industry for the lid to be molded separately from the container and later assembled therewith. This allows one standard size lid to be manufactured for multiple sized containers or vials at a substantial savings in molding expense. For convenience in use, it is desirable that such a hinge hold the lid in at least one predetermined open position so that the lid will not flop freely back into a closed position, thereby making manipulation of the vial difficult.